It supports cases when Person is in middle of requesting of Software
Instance.

User cannot fetch his instance until related sale order is not confirmed.

brctl is the only command which remains mandatory (except if alter_network
is false), as it is used to fetch information from system that even an
unprivileged user can see.

Example use:
PATH=$PATH:/usr/sbin ./bin/slapformat -cdv slapos.cfg

Prepares for incomming monkey-patching.

Output system commands and system-altering functions from python's os
module.

SLA XML is stored on Software Instance, but in many place the dictionary have
to be used.

It will be later used to follow SLA.

Later is shall be used in order to being followed.

It is easier to store on higher level, as pure XML. Other methods will have to
unserialise data from XML, which would be needed anyway in case of storing
them this way.

This reverts commit 79f0aaea.

More code analysis is required in order to being able support required cases
with parameters passed by user.

SlapTool itself shall not force to pass all possible parameters, as slap
library calls it in different ways.

Add support for lack of existence of computer_id and computer_partition_id,
in this case assume that human (person) is logged in by slap library.

Person does not have to be validated to be loggable user,
but Computer or Software Instance validation state is important,
so split to two queries.

Note: No typo in exception.

Two different scenarios are checked, for each start and destroy:

 * two different transactions, so activity tag is used
 * same transaction, so serialize blocking call is called

Whenever software instance is begin started or destroyed new packing list have
to be created. But in both cases it is not desirable to have more then one
active packing list related to current step of state. So dissallow it by
passing tag and checking for its existence. Even more -- serialize in order to
lock operation on one Software Instance in transaction.